1. Technical Field
The present invention relates a base surface processing method of grinding a base surface and smoothing a thinned base surface.
2. Related Art
In the related art, a substrate serving as a base of a MEMS device is ground so that the base is ground to a desired thickness suitable for a device formed, whereby the base is thinned. Thinning of the base is often realized by mechanical grinding using a grinder or the like, and grinding scraps and grinding residues are formed or left on a processing surface subject to grinding. Therefore, base surface processing is performed so that the ground surface is smoothed by wet-etching the processing surface to dissolve the grinding scraps and grinding residues formed on the processing surface, and the grinding residues are dissolved and removed.
JP-A-2002-192730 discloses an ink jet head manufacturing method including bonding a first silicon wafer serving as an electrode portion and a second silicon wafer serving as a vibrating plate, and then, processing a peripheral portion of the second silicon wafer. Specifically, the ink jet head manufacturing method employs a base surface processing method including grinding a region including non-bonded portions of the first and second silicon wafers, and then, processing a surface of the second silicon wafer.
However, when smoothing by wet-etching the processing surface of the ground base surface, since the base other than the ground processing surface is also etched, the base in a non-ground region which does not require smoothing is etched, so that the thickness thereof decreases. As a result, there is a problem in that the rigidity of the base necessary for movement of the base decreases, and the thinned base is broken when the base is moved. However, JP-A-2002-192730 makes no description of this problem.
Thus, there is a demand for a base surface processing method in which when etching the processing surface of the thinned base to smoothen the grinding scraps formed thereon and dissolve and remove the grinding residues, the base other than the processing surface is not dissolved by etching.